This invention relates to artificial vascular grafts and in particular to vascular grafts made with a fluoropolymer surface.
The autogenous saphenous vein or internal mammary arteries are preferred materials for small-diameter arterial replacement but are not always available or suitable, necessitating the use of a prosthetic graft. A variety of synthetic grafts are available for small diameter arterial replacement but their long-term patency has been less than satisfactory due to intimal hyperplasia and thrombosis.
Autologous endothelial cell seeding can reduce the thrombogenicity of synthetic graft surfaces and is gaining acceptance as a useful adjunct to prosthetic graft implantation. However, vascular graft surfaces tend to be poor substrates for cell adhesion and the fraction of seeded cells which adhere in the time frame dictated by graft implantation procedures is relatively low. Some investigators have pre-coated vascular prostheses with various extracellular matrix proteins in an attempt to improve cell adhesion but the poor binding of many of such proteins to graft material also causes cell adhesion to remain poor.
Plasma discharge, the exposure of biomaterials to a plasma or ionized gas, with the resulting creation of functional groups or surface coatings on a material surface have also been used in the preparation of vascular grafts. For example, in U.S. Pat. No. 4,718,907 vascular prosthesis material is provided with a coating of fluorine-containing polymer on its luminal surfaces having a ratio of fluorine to carbon greater than 1.5 to improve patency of the implanted graft. Also, for example, plasma discharge treatment of some vascular prosthesis material in the presence of some non-polymerizing gases (such as ammonia plasma treatment of polystyrene and polytetrafluoroethylene graft material) have been shown to increase protein binding and endothelial cell adhesion.
However, none of these methods have proven entirely successful in providing a small-diameter vascular graft of synthetic material with good endothelial cell attachment for long term patency.
It is therefore an object of the present invention to provide a vascular graft material with improved binding of extracellular matrix proteins such as fibronectin and laminin.
It is also an object of the present invention to provide a vascular graft material with improved binding of endothelial cells for autologous endothelial cell seeding of prosthetic vascular grafts.
It is also an object of the present invention to provide a small-diameter vascular graft prosthesis having improved prospects for long-term patency.